A multiple-input, multiple-output (MIMO) technology means that both a transmitter and a receiver use multiple antennas. The MIMO technology can improve bandwidth without increasing a spectrum resource and an antenna transmit power.
Due to device aging, a temperature change, or the like, after a signal received by an antenna passes through a radio frequency channel formed by multiple devices, a phase may vary. An angle of arrival (AOA) cannot be accurately measured due to signals with different phases. Therefore, radio frequency channel calibration is required.
At present, radio frequency channel calibration is usually performed using a dedicated hardware calibration instrument such as a signal generator or a spectrum analyzer before device delivery. After the device delivery, radio frequency channel phases may be different due to device aging, a temperature change, or the like.